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November 2006

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Subject:
From:
Steve Gregory <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Steve Gregory <[log in to unmask]>
Date:
Mon, 6 Nov 2006 07:34:56 -0600
Content-Type:
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Mornin' Inge!

Holy Mackerel!! That really shows some embrittlement:

http://stevezeva.homestead.com/files/au_embrittlement.doc  

That last picture looks like the bottom of a forest floor! I had a very
small transistor like that one time, and I think I asked the group if I
should tin it. The reason I asked was because it was so small, and I
didn't know if I would damage it by dipping it:

http://www.stevezeva.homestead.com/files/BipolarTransistor.jpg 

I'm pretty sure you told me that I had better remove the gold, and now I
know why!

Well, it's the start of another week. I'm really looking forward to
tomorrow being over. I'm so sick of all the political ads I could
scream!

I know this is Monday, but I got sent a picture over the weekend that
will start your week off with a smile. You need to look closely at all
the facial expressions of everybody in the picture:

http://stevezeva.homestead.com/files/Who_Brought_the_Cat.jpg

Have a great week everybody!

-Steve Gregory-

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ingemar Hernefjord
(KC/EMW)
Sent: Monday, November 06, 2006 3:00 AM
To: [log in to unmask]
Subject: Re: [TN] Gold Embrittlement

Agree,
We degold all microwave SMT small outline transistors ("helicopters"),
because we had catastrophic gold embrittlement problems. The solder
joints were so brittle, that the leads lifted from the pad in the temp
cycle tests. We measured as much as 15 micrometers of gold! The
semiconductor manufacturer meant, that it is a problem to have control
on the gold process on such small parts. What nonsense! Anyway, we are
today suspiscious with many gold plated parts and do degolding rather
than getting embrittlement.

I'll send some pictures to Steve, so you can see what can happen.
Horror!


Inge
  

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Werner Engelmaier
Sent: den 2 november 2006 23:06
To: [log in to unmask]
Subject: Re: [TN] Gold Embrittlement

Hi Amol,
I you have imersion Au, Au-embrittlement is not a problem because there
is not enough Au. Be careful, however, if your PCBs come from China; I
have seen much thicker Au-layers than are possible with iAu.
Calculating the wt% of Au in a soldert joint is an exercise in futility,
because you have to make the assumption--frequently not warranted--that
the SnAu-IMCs are uniformally distributed.
In cases where you suspect thicker Au [and for the matter Ag; which is
equally as bad as Au in causing SJ-embrittlement] deposits, the safest
course of action is to wash the Au (Ag) off by tipping.

Werner

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